html, body {
    height: 100%;
    margin: 0px;
}

.container {
    height: 80%;
    background: #f0e68c;
    display: flex;
    width: 100%;
}

.side {
    width: 20%;
    background-color: lightgray;
    padding: 20px;
}

.main {
    width: 80%;
    background-color: grey;
    padding: 20px;
}